Silicone hydrogel contact lenses have become an important tool in vision correction. A number of techniques have been employed to produce silicone hydrogel contact lenses with hydrophilic surfaces. For example, some silicone hydrogel contact lenses are surface treated with plasma, some silicone hydrogel contact lenses include a hydrophilic polymeric wetting agent in the polymerizable composition used to produce the silicone hydrogel contact lenses, and some silicone hydrogel contact lenses are cast in contact lens molds formed of a polar resin.
Sharma et al U.S. Patent Application Publication US 2008/0143956 discloses silicone hydrogel contact lenses in which a surface of the lens is wrinkled and includes raised ridges extending upward from the lens surface. The wrinkled surface provided on the posterior surface of the lens is said to facilitate fluid exchange between the lens and the cornea of the lens wearer's eye. The lens is a cast molded lens, which is formed before the wrinkled surface is provided to the lens. The formed or cast molded contact lens is initially provided with a modified surface layer, for example, a silicate surface layer, and subsequently this modified surface becomes the wrinkled surface. For example, the surface may be modified by treating it with plasma or other energy. After forming the modified surface layer, the lens is swelled with a polymerizable swelling agent, for example, including ethylenic unsaturation, such that the swelling agent is polymerizable by free radical polymerization. Depending on the amount of swelling, the modified surface layer, for example, the silicate layer, becomes wrinkled to a varying degree. Polymerization of the polymerizable swelling agent serves to stabilize the wrinkled modified surface layer. This multi-step process, particularly surface modification and stabilizing processing after lens formation, is relatively complex and difficult to control, as well as adding to the cost of manufacturing silicone hydrogel contact lenses.
There continues to be a need for new contact lenses having desirable properties, such as surface wettability, and for new methods, for example, cost effective methods, of manufacturing contact lenses with such desirable properties.